Add support for LoongArch64 architecture (#63)

Motivation:

`os-maven-plugin` doesn't recognize `loongarch64` from `os.arch` property.

Modifications:

- Return `loongarch_64` for `loongarch64`.

Result:

- `os-maven-plugin` now supports `loongarch64`.

README.md

@@ -47,6 +47,7 @@
 * `riscv` if the value is `riscv` or `riscv32`
 * `riscv64` if the value is `riscv64`
 * `e2k` if the value is `e2k`
+* `loongarch_64` if the value is `loongarch64`
 
 Note: The bitness part of this property relies on the bitness of the JVM binary, e.g. You'll get the property that ends with `_32` if you run a 32-bit JVM on a 64-bit OS.
 

src/main/java/kr/motd/maven/os/Detector.java

@@ -254,6 +254,9 @@ private static String normalizeArch(String value) {
         if ("e2k".equals(value)) {
             return "e2k";
         }
+        if ("loongarch64".equals(value)) {
+            return "loongarch_64";
+        }
         return UNKNOWN;
     }